This invention relates to an apparatus for the discharge of fusible materials from a container under pressure higher than the normal atmospheric pressure, by compressed air of laboratory purity or compressed from fresh air, furthermore process and apparatus for filling and refilling of such containers.
Appliances used for the discharge of fusible materials under superpressure have been in general use in various alternatives. Best known are the aerosol appliances, where the dispersion takes place from a sealed tank with the aid of freon gas. It is generally known that the gas--despite its favorable mechanical property--has become more and more unpopular for environment- and health-protective reasons, and consequently its use was prohibited in several countries.
The principle of operation is based on the fact, that the freon in the tank is mixed with the liquid to be dispersed and thus it ensures the required propulsive energy at approximately constant rate.
Aerosol is used in the the USA Pat. No. 3 240 331 without internal tube, but with internal tank, and the dispersion takes place upon blending of a two component synthetic resin following the discharge of the tank.
The propellant of the USA Pat. No. 2 559 091 is also aerosol, here the gas is passed through the material to be dispersed by a piercing needle upon screwing together the two tanks, and this composite will be dispersed. The appliance can be refilled, its handling is awkward.
In the USA Pat. No. 3 858 659--where a large cartridge tank with propellant is arranged--the appliance becomes operative with the aid of a piercing needle. The appliance can be refilled, its sealing is rather difficult.
The USA Pat. No. 3 984 034 does not use aerosol, but a tubular plastic tank is encased in the solid sealed tank, a piston from underneath pushes the tank under superpressure in the direction of the nozzle, and the material passes through a needle into the sprayer mechanism.
Operation of the USA Pat. No. 3 619 092 is similar, but here the piston is replaced by gas suitable for the generation of superpressure. The handling and refilling of both appliances are cumbersome.
Attempts are known which are aimed at producing the kinetic energy of the materials to be dispersed with LP or CO.sub.2 gas, although they are extremely harmful to the health and their environment, their carcenogenic effect is nearly certain, and the LP gas is definitely incendiary.
At the same time these gases are not neutral gases, consequently they are applicable for the dispersion of hygienic or industrial agents only at the expense of quality deterioration, while they are definitely unsuitable for the dispersion of drugs.
Such solution is also known where the material to be dispersed is in a plastic /foil/ hose arranged in a tube, which is screwed into a body provided with nozzle and piercing needle, then this assembly is screwed into a further body in which a piston and a high-pressure air-cartridge are arranged. The air is let under the piston by a piercing needle that pushes the hose towards the other needle, whereby the dispersion becomes possible. However, in this case a considerable amount of material is retained, handling of the appliance is very complicated, it is liable to cause accident, and it has numerous parts. Its commercial refilling is nearly impossible.
Its advantage is that the propellant is not in contact with the material to be dispersed.
The essential feature of another construction is that the liquid to be dispersed passes from an enclosed space through a piercing needle into the nozzle by non-purified pressurized air with the aid of an intermediate mechanism (eg. rubber membrane), and the cartridge containing the pressurized air is arranged under the tank. It becomes operative upon screwing together the two parts. In another alternative the cartridge of the pressurized air is arranged in the tank of the medium within a cylindrical container, and it becomes operative with the aid of a piercing needle similarly upon screwing together the two parts. The fundamental fault of each system is that the construction is complicated. Advantage: they can be refilled, though with difficulty. At the same time the appliance has to be unscrewed on each occasion, and the used cartridges and tanks of the fusible medium (hoses, flasks) are discarded and replaced, and in case of Aeronon the propellant cartridge is filled under a pressure of minimum 70 bar, which requires strict safety technique. The discarded material represents waste and is an environment pollutant.
The charging machines of the sprayers filled with aerosol gas (freon, LP, CO.sub.2, dinitrogen oxide) generally function in several steps, i.e. they discharge the liquid, stop mechanically, then charge the propellants in liquid state into the tank where the propellants are absorbed in the liquid. The machines are suitable only for a first filling and not for refilling. The gases retained in the discharged appliance can be checked only with instrument, consequently their refilling is definitely prohibitive.